[Bug rtl-optimization/100311] New: UB in sel-sched.c:init_regs_for

public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed

* [Bug rtl-optimization/100311] New: UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base
@ 2021-04-28  8:37 acoplan at gcc dot gnu.org
  2021-04-28 11:07 ` [Bug rtl-optimization/100311] " rearnsha at gcc dot gnu.org
                   ` (4 more replies)
  0 siblings, 5 replies; 6+ messages in thread
From: acoplan at gcc dot gnu.org @ 2021-04-28  8:37 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100311

            Bug ID: 100311
           Summary: UB in sel-sched.c:init_regs_for_mode with
                    -march=armv8-m.base
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: acoplan at gcc dot gnu.org
  Target Milestone: ---

For the following testcase on arm:

int a;
long long b;
long long c() { return a + b; }

building GCC with -fsanitize=undefined and invoking as:

./arm-eabi-gcc -c test.c -march=armv8-m.base -O2 -fselective-scheduling2

shows the following problems:

/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1080:35: runtime error: index 107
out of bounds for type 'char [107]'
    #0 0x1bad6bc in init_regs_for_mode
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1080
    #1 0x1bad6bc in mark_unavailable_hard_regs
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1242
    #2 0x1bad6bc in find_used_regs
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:3295
    #3 0x1bad6bc in collect_unavailable_regs_from_bnds
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1586
    #4 0x1bad6bc in find_best_reg_for_expr
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1649
    #5 0x1bad6bc in fill_vec_av_set
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:3784
    #6 0x1bb8174 in fill_ready_list
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:4014
    #7 0x1bb8174 in find_best_expr
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:4374
    #8 0x1bb8174 in fill_insns /data_sdb/toolchain/src/gcc/gcc/sel-sched.c:5535
    #9 0x1bb8174 in schedule_on_fences
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7353
    #10 0x1bb8174 in sel_sched_region_2
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7491
    #11 0x1bc2b30 in sel_sched_region_1
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7533
    #12 0x1bc4beb in sel_sched_region(int)
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7634
    #13 0x1bc966d in run_selective_scheduling()
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7720
    #14 0x1b3881c in rest_of_handle_sched2
/data_sdb/toolchain/src/gcc/gcc/sched-rgn.c:3738
    #15 0x1b3881c in execute /data_sdb/toolchain/src/gcc/gcc/sched-rgn.c:3882
    #16 0x1925050 in execute_one_pass(opt_pass*)
/data_sdb/toolchain/src/gcc/gcc/passes.c:2567
    #17 0x1927afc in execute_pass_list_1
/data_sdb/toolchain/src/gcc/gcc/passes.c:2656
    #18 0x1927aba in execute_pass_list_1
/data_sdb/toolchain/src/gcc/gcc/passes.c:2657
    #19 0x1927aba in execute_pass_list_1
/data_sdb/toolchain/src/gcc/gcc/passes.c:2657
    #20 0x1927b57 in execute_pass_list(function*, opt_pass*)
/data_sdb/toolchain/src/gcc/gcc/passes.c:2667
    #21 0xc22722 in cgraph_node::expand()
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:1828
    #22 0xc28a02 in expand_all_functions
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:1992
    #23 0xc28a02 in symbol_table::compile()
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:2356
    #24 0xc33b18 in symbol_table::finalize_compilation_unit()
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:2537
    #25 0x1cc9ceb in compile_file /data_sdb/toolchain/src/gcc/gcc/toplev.c:482
    #26 0x1cd062b in do_compile /data_sdb/toolchain/src/gcc/gcc/toplev.c:2201
    #27 0x1cd062b in toplev::main(int, char**)
/data_sdb/toolchain/src/gcc/gcc/toplev.c:2340
    #28 0x43146ce in main /data_sdb/toolchain/src/gcc/gcc/main.c:39
    #29 0x7ffff6740bf6 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x21bf6)
    #30 0x645bc9 in _start
(/data_sdb/toolchain/build-arm-eabi-armv8-m.base/install/libexec/gcc/arm-eabi/12.0.0/cc1+0x645bc9)

/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1081:43: runtime error: index 107
out of bounds for type 'char [107]'
    #0 0x1bad6e0 in init_regs_for_mode
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1081
    #1 0x1bad6e0 in mark_unavailable_hard_regs
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1242
    #2 0x1bad6e0 in find_used_regs
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:3295
    #3 0x1bad6e0 in collect_unavailable_regs_from_bnds
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1586
    #4 0x1bad6e0 in find_best_reg_for_expr
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1649
    #5 0x1bad6e0 in fill_vec_av_set
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:3784
    #6 0x1bb8174 in fill_ready_list
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:4014
    #7 0x1bb8174 in find_best_expr
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:4374
    #8 0x1bb8174 in fill_insns /data_sdb/toolchain/src/gcc/gcc/sel-sched.c:5535
    #9 0x1bb8174 in schedule_on_fences
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7353
    #10 0x1bb8174 in sel_sched_region_2
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7491
    #11 0x1bc2b30 in sel_sched_region_1
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7533
    #12 0x1bc4beb in sel_sched_region(int)
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7634
    #13 0x1bc966d in run_selective_scheduling()
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7720
    #14 0x1b3881c in rest_of_handle_sched2
/data_sdb/toolchain/src/gcc/gcc/sched-rgn.c:3738
    #15 0x1b3881c in execute /data_sdb/toolchain/src/gcc/gcc/sched-rgn.c:3882
    #16 0x1925050 in execute_one_pass(opt_pass*)
/data_sdb/toolchain/src/gcc/gcc/passes.c:2567
    #17 0x1927afc in execute_pass_list_1
/data_sdb/toolchain/src/gcc/gcc/passes.c:2656
    #18 0x1927aba in execute_pass_list_1
/data_sdb/toolchain/src/gcc/gcc/passes.c:2657
    #19 0x1927aba in execute_pass_list_1
/data_sdb/toolchain/src/gcc/gcc/passes.c:2657
    #20 0x1927b57 in execute_pass_list(function*, opt_pass*)
/data_sdb/toolchain/src/gcc/gcc/passes.c:2667
    #21 0xc22722 in cgraph_node::expand()
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:1828
    #22 0xc28a02 in expand_all_functions
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:1992
    #23 0xc28a02 in symbol_table::compile()
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:2356
    #24 0xc33b18 in symbol_table::finalize_compilation_unit()
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:2537
    #25 0x1cc9ceb in compile_file /data_sdb/toolchain/src/gcc/gcc/toplev.c:482
    #26 0x1cd062b in do_compile /data_sdb/toolchain/src/gcc/gcc/toplev.c:2201
    #27 0x1cd062b in toplev::main(int, char**)
/data_sdb/toolchain/src/gcc/gcc/toplev.c:2340
    #28 0x43146ce in main /data_sdb/toolchain/src/gcc/gcc/main.c:39
    #29 0x7ffff6740bf6 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x21bf6)
    #30 0x645bc9 in _start
(/data_sdb/toolchain/build-arm-eabi-armv8-m.base/install/libexec/gcc/arm-eabi/12.0.0/cc1+0x645bc9)

/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1081:43: runtime error: load of
address 0x000009688beb with insufficient space for an object of type 'char'
0x000009688beb: note: pointer points here
 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00 
00 00 01 01 01 01 01
              ^
    #0 0x1bad6f8 in init_regs_for_mode
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1081
    #1 0x1bad6f8 in mark_unavailable_hard_regs
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1242
    #2 0x1bad6f8 in find_used_regs
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:3295
    #3 0x1bad6f8 in collect_unavailable_regs_from_bnds
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1586
    #4 0x1bad6f8 in find_best_reg_for_expr
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:1649
    #5 0x1bad6f8 in fill_vec_av_set
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:3784
    #6 0x1bb8174 in fill_ready_list
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:4014
    #7 0x1bb8174 in find_best_expr
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:4374
    #8 0x1bb8174 in fill_insns /data_sdb/toolchain/src/gcc/gcc/sel-sched.c:5535
    #9 0x1bb8174 in schedule_on_fences
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7353
    #10 0x1bb8174 in sel_sched_region_2
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7491
    #11 0x1bc2b30 in sel_sched_region_1
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7533
    #12 0x1bc4beb in sel_sched_region(int)
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7634
    #13 0x1bc966d in run_selective_scheduling()
/data_sdb/toolchain/src/gcc/gcc/sel-sched.c:7720
    #14 0x1b3881c in rest_of_handle_sched2
/data_sdb/toolchain/src/gcc/gcc/sched-rgn.c:3738
    #15 0x1b3881c in execute /data_sdb/toolchain/src/gcc/gcc/sched-rgn.c:3882
    #16 0x1925050 in execute_one_pass(opt_pass*)
/data_sdb/toolchain/src/gcc/gcc/passes.c:2567
    #17 0x1927afc in execute_pass_list_1
/data_sdb/toolchain/src/gcc/gcc/passes.c:2656
    #18 0x1927aba in execute_pass_list_1
/data_sdb/toolchain/src/gcc/gcc/passes.c:2657
    #19 0x1927aba in execute_pass_list_1
/data_sdb/toolchain/src/gcc/gcc/passes.c:2657
    #20 0x1927b57 in execute_pass_list(function*, opt_pass*)
/data_sdb/toolchain/src/gcc/gcc/passes.c:2667
    #21 0xc22722 in cgraph_node::expand()
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:1828
    #22 0xc28a02 in expand_all_functions
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:1992
    #23 0xc28a02 in symbol_table::compile()
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:2356
    #24 0xc33b18 in symbol_table::finalize_compilation_unit()
/data_sdb/toolchain/src/gcc/gcc/cgraphunit.c:2537
    #25 0x1cc9ceb in compile_file /data_sdb/toolchain/src/gcc/gcc/toplev.c:482
    #26 0x1cd062b in do_compile /data_sdb/toolchain/src/gcc/gcc/toplev.c:2201
    #27 0x1cd062b in toplev::main(int, char**)
/data_sdb/toolchain/src/gcc/gcc/toplev.c:2340
    #28 0x43146ce in main /data_sdb/toolchain/src/gcc/gcc/main.c:39
    #29 0x7ffff6740bf6 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x21bf6)
    #30 0x645bc9 in _start
(/data_sdb/toolchain/build-arm-eabi-armv8-m.base/install/libexec/gcc/arm-eabi/12.0.0/cc1+0x645bc9)

^ permalink raw reply	[flat|nested] 6+ messages in thread

* [Bug rtl-optimization/100311] UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base
  2021-04-28  8:37 [Bug rtl-optimization/100311] New: UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base acoplan at gcc dot gnu.org
@ 2021-04-28 11:07 ` rearnsha at gcc dot gnu.org
  2021-04-28 16:59 ` cvs-commit at gcc dot gnu.org
                   ` (3 subsequent siblings)
  4 siblings, 0 replies; 6+ messages in thread
From: rearnsha at gcc dot gnu.org @ 2021-04-28 11:07 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100311

Richard Earnshaw <rearnsha at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-04-28
     Ever confirmed|0                           |1

--- Comment #1 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
Suggested fix:
https://gcc.gnu.org/pipermail/gcc-patches/2021-April/569006.html

^ permalink raw reply	[flat|nested] 6+ messages in thread

* [Bug rtl-optimization/100311] UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base
  2021-04-28  8:37 [Bug rtl-optimization/100311] New: UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base acoplan at gcc dot gnu.org
  2021-04-28 11:07 ` [Bug rtl-optimization/100311] " rearnsha at gcc dot gnu.org
@ 2021-04-28 16:59 ` cvs-commit at gcc dot gnu.org
  2021-04-29 10:56 ` cvs-commit at gcc dot gnu.org
                   ` (2 subsequent siblings)
  4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-04-28 16:59 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100311

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Earnshaw <rearnsha@gcc.gnu.org>:

https://gcc.gnu.org/g:59f5d16f2c5db4d9592c8ce6453afe81334bb012

commit r12-222-g59f5d16f2c5db4d9592c8ce6453afe81334bb012
Author: Richard Earnshaw <rearnsha@arm.com>
Date:   Wed Apr 28 17:56:38 2021 +0100

    arm: fix UB due to missing mode check [PR100311]

    Some places in the compiler iterate over all the fixed registers to
    check if that register can be used in a particular mode.  The idiom is
    to iterate over the register and then for that register, if it
    supports the current mode to check all that register and any
    additional registers needed (HARD_REGNO_NREGS).  If these two checks
    are not fully aligned then it is possible to generate a buffer overrun
    when testing data objects that are sized by the number of hard regs in
    the machine.

    The VPR register is a case where these checks were not consistent and
    because this is the last HARD register the result was that we ended up
    overflowing the fixed_regs array.

    gcc:
            PR target/100311
            * config/arm/arm.c (arm_hard_regno_mode_ok): Only allow VPR to be
            used in HImode.

^ permalink raw reply	[flat|nested] 6+ messages in thread

* [Bug rtl-optimization/100311] UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base
  2021-04-28  8:37 [Bug rtl-optimization/100311] New: UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base acoplan at gcc dot gnu.org
  2021-04-28 11:07 ` [Bug rtl-optimization/100311] " rearnsha at gcc dot gnu.org
  2021-04-28 16:59 ` cvs-commit at gcc dot gnu.org
@ 2021-04-29 10:56 ` cvs-commit at gcc dot gnu.org
  2021-04-29 10:56 ` cvs-commit at gcc dot gnu.org
  2021-04-29 10:57 ` rearnsha at gcc dot gnu.org
  4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-04-29 10:56 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100311

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Richard Earnshaw
<rearnsha@gcc.gnu.org>:

https://gcc.gnu.org/g:bda407c9a0da4aacdc62306c85712b93afa1bbc3

commit r11-8328-gbda407c9a0da4aacdc62306c85712b93afa1bbc3
Author: Richard Earnshaw <rearnsha@arm.com>
Date:   Wed Apr 28 17:56:38 2021 +0100

    arm: fix UB due to missing mode check [PR100311]

    Some places in the compiler iterate over all the fixed registers to
    check if that register can be used in a particular mode.  The idiom is
    to iterate over the register and then for that register, if it
    supports the current mode to check all that register and any
    additional registers needed (HARD_REGNO_NREGS).  If these two checks
    are not fully aligned then it is possible to generate a buffer overrun
    when testing data objects that are sized by the number of hard regs in
    the machine.

    The VPR register is a case where these checks were not consistent and
    because this is the last HARD register the result was that we ended up
    overflowing the fixed_regs array.

    gcc:
            PR target/100311
            * config/arm/arm.c (arm_hard_regno_mode_ok): Only allow VPR to be
            used in HImode.
    (cherry picked from commit 59f5d16f2c5db4d9592c8ce6453afe81334bb012)

^ permalink raw reply	[flat|nested] 6+ messages in thread

* [Bug rtl-optimization/100311] UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base
  2021-04-28  8:37 [Bug rtl-optimization/100311] New: UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base acoplan at gcc dot gnu.org
                   ` (2 preceding siblings ...)
  2021-04-29 10:56 ` cvs-commit at gcc dot gnu.org
@ 2021-04-29 10:56 ` cvs-commit at gcc dot gnu.org
  2021-04-29 10:57 ` rearnsha at gcc dot gnu.org
  4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-04-29 10:56 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100311

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Richard Earnshaw
<rearnsha@gcc.gnu.org>:

https://gcc.gnu.org/g:d0ae39ce2c3b4d635de6102ec3750cf6109cdc8d

commit r10-9778-gd0ae39ce2c3b4d635de6102ec3750cf6109cdc8d
Author: Richard Earnshaw <rearnsha@arm.com>
Date:   Wed Apr 28 17:56:38 2021 +0100

    arm: fix UB due to missing mode check [PR100311]

    Some places in the compiler iterate over all the fixed registers to
    check if that register can be used in a particular mode.  The idiom is
    to iterate over the register and then for that register, if it
    supports the current mode to check all that register and any
    additional registers needed (HARD_REGNO_NREGS).  If these two checks
    are not fully aligned then it is possible to generate a buffer overrun
    when testing data objects that are sized by the number of hard regs in
    the machine.

    The VPR register is a case where these checks were not consistent and
    because this is the last HARD register the result was that we ended up
    overflowing the fixed_regs array.

    gcc:
            PR target/100311
            * config/arm/arm.c (arm_hard_regno_mode_ok): Only allow VPR to be
            used in HImode.
    (cherry picked from commit 59f5d16f2c5db4d9592c8ce6453afe81334bb012)

^ permalink raw reply	[flat|nested] 6+ messages in thread

* [Bug rtl-optimization/100311] UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base
  2021-04-28  8:37 [Bug rtl-optimization/100311] New: UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base acoplan at gcc dot gnu.org
                   ` (3 preceding siblings ...)
  2021-04-29 10:56 ` cvs-commit at gcc dot gnu.org
@ 2021-04-29 10:57 ` rearnsha at gcc dot gnu.org
  4 siblings, 0 replies; 6+ messages in thread
From: rearnsha at gcc dot gnu.org @ 2021-04-29 10:57 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100311

Richard Earnshaw <rearnsha at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #5 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
Fixed on all relevant branches.

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2021-04-29 10:57 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-04-28  8:37 [Bug rtl-optimization/100311] New: UB in sel-sched.c:init_regs_for_mode with -march=armv8-m.base acoplan at gcc dot gnu.org
2021-04-28 11:07 ` [Bug rtl-optimization/100311] " rearnsha at gcc dot gnu.org
2021-04-28 16:59 ` cvs-commit at gcc dot gnu.org
2021-04-29 10:56 ` cvs-commit at gcc dot gnu.org
2021-04-29 10:56 ` cvs-commit at gcc dot gnu.org
2021-04-29 10:57 ` rearnsha at gcc dot gnu.org

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).